Wind Turbine Day 7

_Day 7
I couldn’t find U bolts large enough so I ended up getting 3
more suitable plastic drainpipe brackets ($6.87 each), these ones will be ok
but it’s back to the wider 8x4 timber again to be able to mount them. I also
picked up a length of angle iron ($11.51) & a right angle bracket ($11.22)to
make the tail fin.I got 2 adjustable scaffold
legs for $25 each & they look ideal for fitting to each end of my scaffold
pole.
I also picked up a scaffold pole clamp ($9) which I think
will be handy for connecting rope or a cable to when erecting the pole.
At the same place I also picked up a 3 metre length of flat
steel 50mm x 4mm which I’m hoping will be the answer to mounting &
stiffening my home made plastic blades.
Well I hope that’s got the shopping bit over with for a
while, I should have enough bits to be able to have a fully erected &
working wind generator, oh..apart from all the technical wiring stuff but I’m
hoping that will not pose to much of a problem and of course it all needs to be
painted.
Looking forward to this next bit, making the blades &
mounting them, it should start to look like a wind turbine soon. Hopefully.
My PVC storm water pipe has an outside diameter of 160mm
& a circumference of 510mm which is pretty close to 20 inches. The wall
thickness is approx. 3.5mm
The idea is that I’m going to split it length ways into 4
quarters, this would make 4 blades although I only need 3 blades so I will have
a spare.
So based on the pipe I have, each blade should have a max
width of approx 5 inches or 127mm. According to some research the length is
best to be around 5 times the width which would equate to 25 inches or 535mm
long. Other research has suggested 700mm was a good length for this width so in
the end I allowed a bit for fixing to the motor cover & cut the pipe 750mm
long using a very large drop saw which made it easy to keep the cut square.
If you don’t have a large enough saw then it’s back to the
jigsaw, circular saw or my second preference would be a handsaw. To mark the
ends you could always wrap a piece of A3 paper or old squared up wallpaper
around the pipe to help mark it off exactly.
You can also use the paper idea to mark out the quarters,
first put the paper around & mark off it’s circumference. Then with the
paper flat, measure & mark the quarters. Then wrap the paper around the
pipe again & mark the quarters on one end of the pipe. Lay the pipe on a
flat surface with a piece of wood each side to stop it rolling. Now with a
pencil laying flat on top of a small piece of wood run the pencil down the
length of the pipe at each quarter so you should now have the pipe marked out
for each quarter. Update, use a felt tip or permanent marker pen because the
pencil line was difficult to see with so much plastic swarf being in the way
during cutting.
Measure 100mm in from one end & mark a line around the
pipe, you can use the paper for this as well.
Now mark the 50mm tip width at the other end.
Carefully hold masking tape on the 50mm mark & keeping it
fairly tight & straight & lay it down so it lines up with the 100mm line. Do
this for each quarter.
I’ve designed my blades to spin clockwise, just because I
wanted to really, it just wouldn’t feel right going the other way, bad karma or
feng shui or something. Almost forgot, if the blades spin clockwise then the
main fixing nut on the motor cover that will be holding the blades will not
come undone, I guess that’s much more important than feng sui.
Double check all measurements, it needs to be accurate, each
of the blades needs to be exactly the same weight & dimensions to ensure a
stable none vibrating spin, we will be also checking the balance later when
they are mounted. My second hand pipe had been used so I also gave it a good
clean, I may paint it later, not sure what paint to use though.
There are many ways to cut the carefully marked out pipe but
after my initial success with the jigsaw I’m going to use that again.
Success, the jigsaw done it again, next I need to sharpen
the blades, (the turbine blades not the jigsaw) this will make them dangerous
& much more manly but more importantly the leading edge of the blade should
be fairly sharp so it can cut through the air & be much quieter. The
trailing edge can be left square.Again
there are many ways to tidy the blades, I’m going to try a sander & see how
that works. Update, it was going to take too long with a sander so I used a
bench grinder.

I ended up buying 3 new brackets, they were still plastic but they are far stronger than the others & by adding a piece of sticky backed foam inside the whole assembly feels very solid.

Folding paper around the pipe to mark the quarters. The paper needs to have square 90 degree corners for this to work.

Here I've shown the 4 quarters marked out on the paper.

A nice easy way to mark the 4 lengths, but stop the pipe from moving by putting a block of wood either side to stop it rolling.